1. Field of the Invention
The present invention relates to a tabular silver halide photographic emulsion having a silver iodide content of 5 mol % or more, and containing tabular grains having an aspect ratio of 2 or more in an amount of 50% or more of the total projected area of all grains, a method of preparing the emulsion, and a multilayer color photographic light-sensitive material using the emulsion.
2. Description of the Related Art
A method of producing a tabular silver halide photographic emulsion is discussed in detail in, for example, U.S. Pat. No. 4,945,037. The process of grain formation usually consists of a nucleation step, a ripening step, and a growing step. In the process, various techniques are used to control the grain size distribution. However, this document makes no mention of the concentration of iodide in an aqueous halide solution and the concentration of silver salt in an aqueous silver salt solution, added in the growing step, can effect on the distribution of the iodide content between grains.
JP-A-58-113928 ("JP-A" means Published Unexamined Japanese Patent Application) discloses a method of preparing a tabular silver bromoiodide emulsion having an average aspect ratio of 8 or more. However, this document merely states that the concentration of the halide salt added is preferably 0.1 to 5 mol/liter, and does not at all discuss the effect on the distribution of the iodide content between grains that is obtainable with the concentration of iodide in the aqueous halide solution or that of silver salt in the aqueous silver salt solution.
On the other hand, U.S. Pat. No. 4,835,095 discloses an internally silver iodide-rich, tabular silver halide emulsion having an aspect ratio of 5 or more, and having a relative standard deviation of silver iodide content distribution between grains of 20% or less. However, the minimum relative standard deviation of silver iodide content between grains in its Examples is 10%, and makes no mention of the concentration of iodide in the aqueous silver halide solution, or that of silver salt in the aqueous silver salt solution, added.
The present invention is to provide a method in which the relative standard deviation of the silver iodide content distribution is reduced to 8% or less, with clarification of the effect obtainable with the concentration of iodide in the aqueous halide solution added and that of silver salt in the aqueous silver salt solution, added.